Various antireflective polymer films (“AR films”) have been described. The physical principles by which antireflection films and coatings function are well known. Several overviews can be found, for example, in Optical Engineering, S. Muskiant Ed, Vol. 6., Optical Materials, Chap. 7, p 161, 1985 and as shown in U.S. Pat. No. 3,833,368 to Land, et al. AR films are often constructed of alternating high and low refractive index (“RI”) polymer layers of the correct optical thickness. With regards to visible light, this thickness is on the order of one-quarter of the wavelength of the light to be reflected. The human eye is most sensitive to light around 550 nm. Therefore it is desirable to design the low and high index coating thicknesses in a manner that minimizes the amount of reflected light in this optical range (e.g. 3% or lower).
As described in Groh and Zimmerman, Macromolecules, Vol. 24 p. 6660 (1991), it is known that fluorine containing materials have a low refractive index and are therefore useful in the low refractive index layer of AR films.
Various AR coatings using fluoro(meth)acrylate polymers and fluorine containing materials have also been described.
Although increased fluorine content decreases the refractive index of the low refractive index coating composition, the concurrent decrease in surface energy can result in poor coating and optical cosmetic properties as well as a loss in interfacial adhesion with the adjacent high refractive index layer. Also, highly fluorinated materials have been known to reduce the hardness and durability of the coating.